The present invention relates to an integrated circuit conveying rail for use in an IC tester, for example, and more particularly, to a rail for conveying integrated circuits with J-shaped leads.
A description will be given first, with reference to FIGS. 1A, 1B, 2A, 2B and 3A, 3B, of three conventional rails for conveying integrated circuits (hereinafter referred to as ICs) with J-shaped leads. In the case of testing a number of ICs 5 in an IC manufacturing process, IC conveying rails 10 are needed to convey the ICs to an IC testing section in a sequential order and convey tested ICs from the IC testing section to an unloading section where the tested ICs are sorted and loaded accordingly. Such an IC tester is disclosed in, for example, U.S. Pat. No. 4,691,831 or 4,715,501.
FIGS. 1A, 1B, 2A, 2B and 3A, 3B are cross-sectional views of the IC conveying rail 10 and the IC 5 which is conveyed thereon. The rail 10 is formed by a cascade connection of a plurality of rail units each of which has a rectangularly-sectioned channel groove 2 for receiving and guiding ICs 5 and is long enough to receive a plurality of ICs 5. Reference numeral 3 indicates side wall of the channel groove 2. The rail 10 slides thereon the ICs 5 to convey them in succession from a loading section to the IC testing section and thence to the unloading section, but since the ICs 5 are distributed to a plurality of rails or reversed in direction on their way to the testing section or unloading section, some rail units are abruptly translated in the lateral direction or some other rail units are abruptly turned around. Thus, some rail units are abruptly driven, and consequently, the ICs mounted on such rail units receive great shocks in directions other than that in which they are conveyed; therefore, after mounting the ICs 5 on the rail 10, a roof 4 extending along the channel groove 2 is disposed above the rail 10 to prevent the ICs 5 from jumping up. Reference numeral 7 denotes a molded portion of each IC 5.
When the rail 10 is abruptly driven as mentioned above, the ICs 5 collide against side walls 3 in the channel groove 2 of the rail 10, with the result that J-shaped leads may sometimes be deformed. In the example shown in FIGS. 1A and 1B the channel groove 2 is so deep that the leads 6 are almost hidden, and the side walls 3 are upright at right angles to the bottom 2B of the channel groove 2. This prior art example is a lead guide type wherein the ICs 5 are guided in the channel groove 2 by the leads 6 alone, and when the rail 10 is abruptly driven as mentioned above, the leads 6 may sometimes collide at their tip end portions P with the side walls 3 as depicted in FIG. 1B. Since the tip end portion P of each lead 6 is appreciably apart from its base, the shock that the tip end portion P receives from the side wall 3 applies a great bending stress to the base of the lead 6 through leverage, deforming the lead 6 in some cases.
The prior art example of FIGS. 2A and 2B is a mold guide type wherein the channel groove 2 is shallow and the ICs 5 are guided by the lower half portions 7B of their molded portions 7 although the side walls 3 are perpendicular to the bottom 2B of the channel groove 2 as is the case with the example of FIGS. 1A and 1B. In this instance, the leads 6 may be deformed by collision with the roof 4. When the channel groove 2 is formed shallow corresponding to the thickness of the lower half portion 7B of the molded portion 7 indicated by H in FIG. 3A, there is a case where the ICs 5 get out of the channel groove 2 as depicted in FIG. 3B. Also in this case, the leads 6 may be deformed by stress.